Macroscopic quantum phenomena in superconducting neutron stars are directly linked to their observable signatures.
For example, protons superconductivity is expected in the core of NS and is a crucial problem in many aspects of rotational and magnetic evolution of pulsars and magnetars.
The response of matter to the magnetic field is a fundamental property and it is conveniently expressed in terms of superconductivity type.
The type of superconductivity relevant to uniform nuclear matter was first analyzed at typical conditions in the core of NS by Baym, Pethick and Pines (1969) in the framework of a single-component superconductor (influence of SF neutrons was discarded) [1]}.
The conclusion was that type-II is expected because the GL parameter in NS matter is around 3, while the critical GL parameter \(\kappa _c\)  for a single-component SC is equal to \(1/\sqrt{2}\) .
However, the SF state in the NS interior is expected to have more than one scalar (proton) condensate and it is important to understand multicomponent SF effects arising from the nuclear interactions.
Coupling of the stellar angular momentum to the MF is set by the vortex-flux tube interactions (or their absence) [2]}, [3]}, [4]}.
The magnetic stresses and arrangement of the MF lines in the NS interior are also influenced by the core superconductivity [5]}, [6]}.
